Also, on a fan there will be four struts from the centre to the edge,
if you plug the fan in and hold this side facing you, you will feel the breeze,
alternatively, see the side with the blades and spinning bit in the middle, if that is visible from the outside of the case, then that fan is blowing into the case,
does that clear it for you?
my explanations are sometimes a little vague to 'normal' people hehe